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Thread: Mobile Users Beware: Linux Has Major Power Regression

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  1. #1
    Join Date
    Jan 2007
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    Default Mobile Users Beware: Linux Has Major Power Regression

    Phoronix: Mobile Users Beware: Linux Has Major Power Regression

    For those that follow my personal Twitter feed will know that for the past week I've been closely testing Ubuntu 11.04 and all Ubuntu releases going back to Ubuntu 8.04 on many mobile devices in the office. The overall system performance, power consumption, and boot performance have been the principal targets. However, late this week I discovered a glaring regression: Ubuntu 11.04 is viciously going through power. Compared to Ubuntu 10.10, the power consumption on Ubuntu 11.04 for mobile devices is up about 10% on average but under some workloads, I am seeing the power consumption up by nearly 30%. This is happening on many mobile systems spanning multiple generations of Intel CPUs and with Intel / ATI / NVIDIA graphics. This issue has been tracked down to a frightening kernel regression in the mainline tree that is still not addressed.

    http://www.phoronix.com/vr.php?view=15926

  2. #2
    Join Date
    Oct 2009
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    Blame me, but I'm thinking that latest kernels put the lamp at 100% by default instead older kernels put the lamp at 50% (kidding, but not really seriously) ... how is it possible for such a different hardware to behave all the same way?

  3. #3

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    Quote Originally Posted by blackshard View Post
    Blame me, but I'm thinking that latest kernels put the lamp at 100% by default instead older kernels put the lamp at 50% (kidding, but not really seriously) ... how is it possible for such a different hardware to behave all the same way?
    The screen brightness is unchanged.

  4. #4
    Join Date
    Jul 2009
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    Id really much appreciate an explanation for the X-axis for the Graphs.
    In most cases its time. But it doesnt make sense when you have idling...
    Why are graphs ending at different times if not caused by increased performance?

  5. #5
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    Jul 2009
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  6. #6
    Join Date
    Jan 2010
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    87

    Default Even worse?

    It isn't clear if the power measurements are for the whole system or just the processor. I'm assuming they are for the whole system (ie including screen, drives etc). If that is the case then this problem is even worse. It is reasonable to believe that those physical devices are consuming the same amount of power as before.

    If the devices consumed half the power and the cpu etc consumed the other half then the overall number going up by 10% means all of that increase came from that half of the system. (Sort of the inverse of Amdahl's law.)

  7. #7
    Join Date
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    It boggles the mind how after so many years the rest of the world is still trying to catch up to OS X's power management. You would think in this day and age that it would be common knowledge how to do it properly and not be some black obelisk.

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